Japanese thought of territorial waters in the Edo era developed connecting with the coastal fishery and being influenced by the approach of foreign ships. In Cremean War 1854, Japan rejected the demand of England on mainting neutrality. In Prussian-French War 1870, Japan declared the neutrality and accented the theory of 3-miles territorial waters. But the system of Japanese waters has not been legislated till 1977. Kairi, Hiro, Shaku and Knot were introduced by the Meiji Government. Especially Kairi took the lead in the history of adoption of the metric system.